JP3412362B2 - Exhaust particulate processing equipment for internal combustion engines - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an exhaust particle processing apparatus for collecting particles contained in exhaust gas of an internal combustion engine and treating the collected exhaust particles.

[0002]

2. Description of the Related Art Conventionally, in order to prevent exhaust particulates (particulates) such as soot contained in exhaust gas of an internal combustion engine from being discharged into the atmosphere, a filter element made of ceramic or the like is provided in an exhaust passage. An exhaust particulate treatment device that collects exhaust particulate by this filter element is used.

However, if the collected exhaust particulates are deposited on the filter element, clogging of the filter element increases the exhaust pressure, resulting in deterioration of engine performance and deterioration of fuel consumption. A heating means such as a heater is provided, and the collected exhaust fine particles are burned and removed by the heating means after the internal combustion engine is stopped to regenerate the filter element (see Japanese Patent Laid-Open No. 4-224218).

[0004]

However, in the conventional exhaust particulate treatment apparatus, the regeneration air is insufficient during the regeneration treatment of the filter element, which leads to a reduction in regeneration efficiency. Therefore, a filter incorporating the filter element is used. An exhaust particulate treatment device has been conceived in which a plurality of outside air communicating portions are provided in the case, and natural convection is generated in the filter case at the time of regeneration processing of the filter element so that regeneration air can be efficiently supplied.

However, in such an exhaust particulate treatment apparatus, since the exhaust particulates deposited on the filter element are burned by the regeneration air supplied by natural convection, the upper side of the filter element is more easily heated than the lower side. However, there is a problem in that it is difficult to evenly distribute the heat generated by the heater over the entire filter element. In addition, there is also a demand to reduce the amount of electricity supplied to the heater as much as possible to suppress the power consumption of the battery because the filter element is regenerated after the internal combustion engine is stopped.

In view of the conventional problems as described above, the present invention uses natural convection to increase the temperature of the entire filter element by making the heat generation amount of the heater on the lower side of the filter element larger than that of the heater on the upper side. It is an object to make the heater uniform and reduce the power consumption of the heater.

[0007]

For this reason, the invention according to claim 1 is provided with a filter case having a substantially hollow cylindrical filter element for trapping exhaust particulates in exhaust gas, which is provided in an exhaust passage of an internal combustion engine. In the exhaust particulate treatment device for an internal combustion engine, in which the filter element is regenerated by burning and removing the collected exhaust particulate by an electric heater, the electrothermal heater is formed of a thin conductor.
It has a cylindrical shape that fits inside the filter element.
There is a circle so that heat is generated due to an increase in electrical resistance.
It is a configuration in which a slit is provided on the cylindrical peripheral wall,
The slit on the lower side in the vertical direction of the electric heater,
Make it denser than the slit on the upper side in the vertical direction
Then, the amount of heat generated on the lower side in the vertical direction of the electric heater is made larger than the amount of heat generated on the upper side in the vertical direction.

[0008]

According to a second aspect of the present invention, the slit in the lower half of the electric heater in the vertical direction is formed more densely than the slit in the upper half in the vertical direction. According to a third aspect of the present invention, the slits are formed so as to continuously change from dense to coarse from the lower portion to the upper portion in the vertical direction of the electric heater. Contract
In the invention according to claim 4 , when the filter element is substantially horizontal and a plurality of the filter elements are arranged in parallel in a substantially vertical direction, a slit of an electric heater fitted to the filter element is provided. Even in the case where a plurality of electric heaters are arranged in parallel, the lower side is denser than the upper side in the vertical direction.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, the structure of the exhaust particulate treatment system which is the premise of the present invention will be described. 1 and 2 show a vertical or horizontal exhaust particulate treatment apparatus, which is made of a hollow cylindrical ceramic or the like having a heater 105 in an exhaust passage 101 connected to an exhaust manifold of an internal combustion engine (not shown). A filter case 102 in which a porous filter element 104 is installed substantially vertically (FIG. 1) or substantially horizontally (FIG. 2) is interposed. The filter element 104 introduces the exhaust gas from the engine from the open end on the exhaust upstream side into the inner peripheral portion of the hollow cylinder, but since the end portion on the exhaust downstream side is closed as described later, the inner peripheral portion is closed. The exhaust gas introduced into the section is passed to the outer peripheral portion of the hollow cylinder. That is, when the exhaust gas passes from the inner peripheral side to the outer peripheral side of the hollow cylinder, the exhaust particulates in the exhaust are collected by the filter element 104.

A heater 105 for electrically heating and burning the exhaust particulates collected by the filter element 104.
Is SUS system or Fe-Cr-Al system, or Ni
A thin-plate electric heating element (electric conductor) of the —Cr—Fe system is used, and is formed in a cylindrical shape so as to fit to the inner circumference of the hollow cylinder of the filter element 104. In the present embodiment, the heater 105 is provided so as to be inscribed on the inner peripheral surface of the hollow cylinder of the filter element 104, that is, the inflow surface of the exhaust gas, but inside the filter element 104,
Alternatively, it may be provided on the outer peripheral surface.

Further, the exhaust gas downstream side of the heater 105 is closed by a closing portion 105b composed of a plate-like member,
An electrode 105a for energizing the heater 105 is provided on the closed portion 105b, and the electrode 105a is electrically insulated from the filter case 102 and led out to the outside. On the other hand, the exhaust upstream side opening 105c is
It is grounded by the filter case 102. The electrode 105a includes a regeneration switch, a regeneration timer / relay,
It is connected to a battery through a heater drive circuit 106 including a regeneration / warning lamp and the like, and is electrically heated for a predetermined time, for example, 10 minutes, through the battery under a predetermined condition and when the engine is stopped as described later. It has become so. Further, a plurality of outside air communicating portions 107 for introducing outside air as regeneration air during regeneration processing of the filter element 104 are formed on the lower peripheral wall of the filter case 102.

In the exhaust passage 101 on the upstream side of the filter element 104, there is provided a filter element regeneration timing detecting means 111 including an exhaust pressure sensor for detecting the regeneration timing of the filter element 104, The output is input to the regeneration timer relay that constitutes the heater drive circuit 106. Next, the operation of the above exhaust particulate treatment device will be described.

When the exhaust particles are collected by the filter element 104, the exhaust particles are collected from the inner circumference to the outer circumference of the filter element 104 so that the exhaust particles are collected by the filter element 104 at the time of passage. Exhaust gas is exhausted to the outside of the vehicle through the exhaust port 103 and a silencer (not shown). When it is time to regenerate the filter element 104, the heater driving circuit 106 is driven after the engine is stopped, and the regeneration heater 105 is energized to start regeneration of the filter element 104. Specifically, for example, when the output value of the exhaust pressure sensor exceeds a predetermined value, it is determined that the regeneration time has come, and the heater drive circuit 1
By turning on the regeneration / warning lamp of No. 06, the driver or the like is informed of the arrival of the regeneration time, and the driver or the like who sees this turns on the regeneration switch to energize the regeneration heater 105 and the filter element 104. Start playing. If the exhaust pressure detected by the exhaust pressure sensor exceeds a specified value, the ignition switch will turn off.
It is also possible to automatically start energizing the heater 105 later. Due to the electric heating of the heater 105, the exhaust particulates deposited on the filter element 104 are ignited and burned, and the filter element 104 is regenerated.

In the regeneration treatment process of the filter element 104, when the exhaust particulates deposited on the filter element 104 start to burn, natural convection toward the upper portion of the filter case 102 is caused by the heated regeneration air. It is generated and discharged to the outside of the vehicle through the exhaust port 103 and a silencer (not shown). Further, the outside air is introduced into the filter case 102 from the outside air communicating portion 107 provided on the peripheral wall of the filter case 102, and the regeneration air is sequentially supplied to the filter element 104 by natural convection.

Next, the constitution peculiar to the exhaust particulate treatment system of the present invention will be explained based on embodiments. 3, 請
In the first embodiment of the heater according to the invention of claim 1 or 2, in the cylindrical heater 105 in the vertical exhaust particulate treatment apparatus, the peripheral wall of the heater 105 is arranged so that the amount of heat generation increases due to an increase in electrical resistance. Slits 108 are provided, and the slits 108 are densely formed in a substantially lower half in the vertical direction and coarsely formed in a substantially upper half in the vertical direction. According to such a configuration, in the dense portion (approximately the lower half) of the slit 108, the increase in the electric resistance is large and the amount of heat generation is significantly increased. The increase in volume is slight. That is, heater 1
The heat generation amount of 05 is larger in the lower part than in the upper part.

In the exhaust particulate treatment apparatus having such a heater 105, when the filter element 104 is regenerated, the temperature below the filter element 104 becomes the highest. Then, the temperature of the regeneration air existing around the lower portion of the filter element 104, which has reached a high temperature, is raised, and the filter element 104 located above it is heated by natural convection. That is, the heat of the filter element 104 is sequentially transferred upward. That is, the upper portion of the filter element 104 has the heater 105.
And the heat generated by the heater 105 at this position is heated by heat transfer.
Even if it is less than the heat generation amount of the filter element 104, the filter element 104 as a whole can be heated to a substantially uniform temperature. Further, since the amount of heat generated in the upper part of the heater 105 is small, it is possible to reduce the power consumption as a whole.

The structure of the heater 105 in the first embodiment described above can be applied to a horizontal exhaust particulate treatment apparatus having the filter element 104 installed substantially horizontally as shown in FIGS. 2 and 4. it can. In this case,
The slit 108 is formed in the lower half of the heater 105 in the vertical direction.
Are densely formed, and the slits 108 are roughly formed in the upper half. The operation and effect of this heater 105 are the same as those of the above-mentioned vertical exhaust particle treatment apparatus, and therefore the description thereof is omitted here.

FIG. 5 shows a second embodiment of the heater according to the invention as defined in claim 3 , in which the slit 108 provided on the peripheral wall of the cylindrical heater 105 in the vertical exhaust gas treatment apparatus is arranged in the vertical direction. It is formed so as to change continuously from dense to coarse from the lower part to the upper part. According to this structure, the amount of heat generated by the heater 105 is the largest in the lower part in the vertical direction, and gradually decreases from the upper part to the upper part.

In the exhaust particulate treatment apparatus having such a heater 105, when the regeneration treatment of the filter element 104 is performed, the heat of the lower portion of the filter element 104 is successively transferred upward as in the first embodiment. However, since the heat generation amount of the heater 105 is continuously changing, such heat transfer is continuously performed over the entire length of the filter element 104. That is, the filter element 104 can be heated to a more uniform temperature as compared with the first embodiment. Therefore, the filter element 1
The heating of 04 can be performed more effectively, and the power consumption as a whole can be further reduced.

The configuration of the heater 105 in the second embodiment described above can also be applied to a horizontal exhaust particulate processing apparatus. In this case, the structure of the heater 105 and its operation and effect are substantially the same as those of the second embodiment described above, and therefore the description thereof is omitted here. Figure 6 billing
In the third embodiment of the heater according to the invention of Item 4 , a plurality of (two in this embodiment) filter elements 104 are arranged in parallel in order to improve the ability to collect exhaust particulates discharged from the internal combustion engine. This is a horizontal exhaust particulate treatment device installed in. The respective filter elements 104 are placed substantially horizontally, and these filter elements 104 are placed in parallel in the substantially vertical direction. Slit 108 of heater 105 fitted to each filter element 104
Are formed so that the lower part is denser than the upper part in the vertical direction.
Even when a plurality of such heaters 105 are combined, the slit 108 as a whole is formed so that the lower part is denser than the upper part in the vertical direction. In other words, the slits 108 in the heater 105 are denser in the lower portion than the upper portion in the vertical direction when the heaters 105 are individually or combined as a whole.

In the horizontal exhaust gas treatment apparatus having such a heater 105, when the filter element 104 is regenerated, each filter element 1
Regarding No. 04, as in the first embodiment, the heat of the lower part of the filter element 104 is sequentially transferred upward, but in this embodiment, the heat generated by the heater 105 fitted to the plurality of filter elements 104 is generated. Since the amount is continuously changing as a whole, each filter element 1 can be efficiently used as compared with the case where only the single heater 105 is combined.
04 can be heated, and the power consumption as a whole can be reduced.

[0023]

As described above, according to the first aspect of the present invention, the heating value on the lower side in the vertical direction of the electric heater for burning and removing exhaust particulates is made larger than the heating value on the upper side in the vertical direction. The temperature at the bottom of the filter element becomes the highest, and the heat is transferred to the filter element located at the upper part through the regeneration air by natural convection, and the heat generation amount at the upper side of the electric heater is at least almost uniform over the entire filter element. It can be heated to various temperatures. Also,
Since the amount of heat generated on the upper side of the electric heater is small, it is possible to reduce the overall power consumption.

At this time, the electric heater is formed into a cylindrical shape that fits into the inner circumference of the filter element made of a thin plate conductor, and a slit for changing the amount of heat generated by increasing the electric resistance is formed on the peripheral wall. Therefore, the electric heater can be easily manufactured, and the number of manufacturing steps can be reduced and the cost can be reduced. Further, since the slits on the lower side in the vertical direction of the electric heater are formed more closely than the slits on the upper side in the vertical direction, the lower side of the electric heater has a large increase in electric resistance, and thus the amount of heat generated is large.
On the other hand, on the upper side of the electric heater, the amount of heat generation is small because the increase in electric resistance is small, and the entire filter element can be heated to a substantially uniform temperature during regeneration processing.

According to the second aspect of the present invention, since the slits in the lower half of the vertical direction of the electric heater are formed more closely than the slits in the upper half of the vertical direction, reproduction is possible without complicated slit forming processing. The entire filter element during processing can be heated to a substantially uniform temperature. Claim
According to the invention of Item 3 , since the slits are formed so as to change continuously from the lower part to the upper part in the vertical direction of the electric heater, the amount of heat generated by the electric heater continuously changes over the entire length of the electric heater. It is possible to heat the entire filter element during the regeneration process to a more uniform temperature as compared with the electric heater according to the second aspect of the present invention.

According to the fourth aspect of the present invention, when the filter elements are arranged substantially horizontally and a plurality of filter elements are arranged substantially vertically in parallel, a plurality of electric heaters are arranged in parallel as a whole. Since the slits are formed so that the lower side is denser than the upper side in the vertical direction, it is possible to efficiently heat the respective filter elements, as compared with the case where the independent heaters are simply arranged in parallel. Power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is an overall view of a vertical exhaust particulate processing apparatus that is a premise of the present invention.

FIG. 2 is an overall view of the horizontal exhaust particle treatment apparatus of the same as above.

FIG. 3 is a detailed view of a heater according to an embodiment of the invention as defined in claim 1 or 2 .

FIG. 4 is a detailed view of a heater according to another embodiment of the above.

FIG. 5 is a detailed view of a heater of an embodiment according to the invention of claim 3 ;

6 shows a heater details of one embodiment according to the invention of claim 4, wherein, (a) represents a front view, (b) is a side view

[Explanation of symbols]

101 exhaust passage 102 filter case 104 filter elements 105 heater 108 slits

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01N 3/02 H05B 3/40

Claims (4)

(57) [Claims] 1. An exhaust passage of an internal combustion engine is provided with a filter case having a substantially hollow cylindrical filter element for collecting exhaust particles in exhaust gas, and the collected exhaust particles are burned and removed by an electric heater. In the exhaust particulate treatment device for an internal combustion engine, wherein the filter element is regenerated, the electrothermal heater is formed of a thin plate electric conductor,
It has a cylindrical shape that fits inside the filter element.
The cylindrical shape to generate heat due to the increase of electric resistance
The peripheral wall has a slit, and the electric heat
The slit on the lower side of the heater in the vertical direction is
The exhaust gas fine particle treatment apparatus for an internal combustion engine , wherein the heat generation amount on the lower side in the vertical direction of the electric heater is made larger than the heat generation amount on the upper side in the vertical direction by forming the slit more densely than the slit on the upper side . 2. A slot in the lower half of the electric heater in the vertical direction.
Is formed more closely than the slit in the upper half of the vertical direction.
Exhaust particulate processing device for an internal combustion engine according to claim 1, wherein a. 3. The electric heater is arranged from the lower part to the upper part in the vertical direction.
As a result, the slits change from dense to coarse continuously.
The exhaust particulate treatment device for an internal combustion engine according to claim 1 , wherein the exhaust particulate treatment device is formed as described above . 4. The filter element is substantially horizontal,
Multiple filter elements are arranged vertically in parallel in the vertical direction.
If it is configured to fit, it fits into the filter element
The slits of the electric heater
As a whole arranged in rows, the lower side than the upper side in the vertical direction
Are formed to be dense.
4. The exhaust particulate treatment device for an internal combustion engine according to any one of 3 .